1. A wear-resistant high-temperature-resistant composite sealing material for sealing a device to be sealed, comprising:

a high temperature resistant elastomer as a core layer configured to be high temperature resistant and elastic; and

the high-temperature-resistant and wear-resistant layer is made of non-metallic materials, covers the outside of the high-temperature-resistant elastomer and is configured to resist high temperature and wear;

when a device to be sealed extrudes the high-temperature-resistant and wear-resistant layer, the high-temperature-resistant and wear-resistant layer and the high-temperature-resistant elastomer are sequentially deformed due to the extrusion, and the high-temperature-resistant elastomer generates resilience force due to the deformation; the non-metallic high-temperature resistant anti-wear layer is configured in such a way that when the device to be sealed is far away from the high-temperature resistant anti-wear layer, the resilience force of the high-temperature resistant elastomer is enough to drive the high-temperature resistant anti-wear layer to move towards the device to be sealed so as to keep the device to be sealed in contact with the high-temperature resistant anti-wear layer and seal the device to be sealed; when the device to be sealed rubs with the composite sealing material, the high-temperature resistant and wear-resistant layer directly contacts with the device to be sealed to generate friction, so that the friction is prevented from directly acting on the high-temperature resistant elastomer, and the friction damage of the high-temperature resistant elastomer is reduced or prevented.

2. The composite sealing material of claim 1, wherein the percentage of the cross-sectional area of the high temperature resistant elastomer to the cross-sectional area of the high temperature resistant abrasion resistant layer is greater than 35% and less than 85% to extend the sealing time of the high temperature resistant abrasion resistant layer to the device to be sealed according to the roughness of the device to be sealed.

3. The composite sealing material according to claim 1, wherein the high temperature resistant elastomer is made of a fluoroelastomer or is made of a TD350 sealing material.

4. The composite sealing material of claim 1 wherein said high temperature and abrasion resistant layer is made of aramid fibers.

5. The composite sealing material according to claim 1, wherein said high temperature resistant and wear resistant layer is impregnated with a high ignition point lubricating material to impart self-lubricity to said high temperature resistant and wear resistant layer.

6. The composite sealing material according to any of claims 1 to 5, wherein the cross-sectional shape of the high temperature resistant elastomer is circular and the cross-sectional shape of the high temperature resistant and wear resistant layer is square or circular.

7. A seal made from the wear and high temperature resistant composite seal material of claim 1.

8. The seal of claim 7, wherein said seal is helically wound from said composite sealing material.

9. A seal according to claim 7, wherein the high temperature and wear resistant layer is square or circular in cross-section, preferably the seal is cylindrical or conical.

10. The sealing element according to any one of claims 7 to 9, wherein the device to be sealed is a polish rod, the upper end of the sealing element is provided with a sealing ring, the sealing ring is made of the high-temperature resistant elastomer, the hardness of the sealing ring is greater than that of the sealing element, the sealing ring is used for preventing the sealing element from being damaged due to the direct action of axial pressure on the sealing element, and the sealing ring has certain deviation correction compensation performance due to the greater hardness when axial runout and eccentricity of the polish rod occur.

Background

How to solve the sealing problem under the extreme working condition of high temperature is a main development direction of sealing materials. The perfluoro-ether rubber can resist the high temperature of 325 ℃, but is not wear-resistant, so that the sealing element is easy to be damaged due to wear, and the sealing failure is caused. For example, in the process of oil extraction in an oil field, the sucker rod makes an axial reciprocating motion to pump oil at the bottom of the ground to the ground, and in order to smoothly realize high-efficiency oil pumping, good radial contact pressure is required between the outer diameter of the polish rod and the inner diameter of a packing in the packing box to realize sealing. The oil-gas mixture in the oil well can corrode the packing due to high temperature and high pressure, the sealing clearance can be gradually increased to generate leakage, and the packing box or the packing in the box needs to be frequently replaced to prevent the bottom oil-gas mixture from being sprayed out so as to ensure the safety of operating personnel. Because of packing frequent damage, the ground bottom oil-gas mixture also can spout at the change packing in-process, there is the hidden danger in operation personnel's safety.

In order to reduce the replacement time of the packing, CN2007201519389 discloses a technical scheme of a spring type spiral sucker rod packing, the spring type spiral sucker rod packing comprises a packing body and a spiral notch arranged on the side wall of the packing body, and the packing is in an integral spring shape, so that the compressibility of the packing is increased, and the packing can be screwed out of the sucker rod from the upper end of the packing when the packing is seriously worn, thereby reducing the replacement time. In order to improve the wear resistance of the packing, CN2014200044467 discloses a "hydrogenated nitrile christmas tree sucker rod packing box sealing ring", and the background technology of the scheme indicates that: the primary reasons for the failure of the sealing element are that the existing common packing is sensitive to the abrasion resistance and temperature difference, and the installation condition is poor, so that the sealing element is sensitive to impact and vibration caused by the increase of the frequency of impact, the service life of a vulnerable part is short and sudden, and the sealing element is easy to fail to cause safety accidents. Therefore, the technical scheme that the packing is made of hydrogenated nitrile rubber instead of a material is adopted, the integral spiral structure is adopted, the conical ring surface is arranged at the front end of the integral spiral structure, the chamfer is arranged to prevent stress concentration of the sealing ring and protect the sealing piece, and the sealing performance is improved. Hydrogenated nitrile rubber is used as a main sealing material, has the characteristics of high pressure resistance of more than 30MPa, high temperature resistance of more than 180 ℃ and service life improvement, and has the advantages of high abrasion loss of 0.2CC and good abrasion resistance. Under the actual working condition, when the gas injection temperature reaches 180 ℃, the sealing of the ordinary nitrile rubber packing or the hydrogenated nitrile packing does not lose effectiveness within 2 days.

Although technicians develop various packing sets, the polish rod and the packing set with the sealing function are in a long-term dynamic wear state along with the up-and-down reciprocating motion of the polish rod driven by the oil pumping unit. And as the abrasion continues to occur, the packing pressing cap needs to be screwed down again. When the packing pressing cap is screwed down to a certain degree, the packing pressing cap is screwed down again and does not work, and at the moment, the pumping unit needs to be shut down and powered off, and the blowout preventer on the lower part of the pumping unit is closed. After all the preparation works are finished, the packing pressing cap is turned and unscrewed, the old packing is taken out by a special hook, and a new packing is installed. Before the new packing is installed, lubricating grease is coated on the surface of the new packing, and then the new packing is installed in a packing box. Then packing pressing sleeves are installed, and packing pressing caps are screwed down. Change the packing of packing box, not only increased workman's work load, more importantly, at the in-process of shutting down, the grit in the oil pipe produced oil can sink, after the packing in the packing box of having changed well, often can appear sand card or wax card accident, whole oil well just need be overhauld, and the maintenance cost also can further increase.

Therefore, it is desirable to develop a wear and high temperature resistant composite seal material and a seal made from the seal material.

Disclosure of Invention

Under the actual working condition, when the gas injection temperature reaches 180 ℃, the sealing of the ordinary nitrile rubber packing or the hydrogenated nitrile packing does not lose effectiveness within 2 days. The inventor finds out through research that: on one hand, the surface of the sucker rod becomes rough due to long-term oil extraction, the sucker rod packing is greatly abraded in a large amount of reciprocating motion, and the sealing of the worn packing is invalid; on the other hand, the pumping rod packing is softened and the wear resistance is reduced under the high-temperature working condition, so that the wear degree is further increased; on the other hand, the elasticity of the packing of the sucker rod is reduced under the high-temperature working condition, and the packing cannot be rebounded and sealed at the worn part; in another aspect, the temperature of the steam injected from the well head is as high as 350 ℃, the temperature of the oil-gas mixture returning to the well head from the bottom of the ordinary well is different due to the gas injection time and the stuffy well time, the temperature of the oil-gas mixture returning to the well head from the bottom of the ordinary well is different due to the different gas injection time in the SAGD well, and the temperature of the oil-gas mixture returning to the well head can even reach 300 ℃. However, the limit temperature of the existing common nitrile rubber packing and hydrogenated nitrile packing is 177 ℃ and cannot resist the high temperature of 180 ℃. Based on this, an object of the present application is to provide a wear-resistant and high-temperature-resistant sealing material and a sealing member to meet the sealing requirements of high wear and high temperature; it is yet another object of the present application to provide a wear resistant, high temperature resistant seal to increase the seal life of a packing box.

According to one aspect of the application, a wear-resistant and high-temperature-resistant composite sealing material is provided for sealing a device to be sealed, and comprises:

a high temperature resistant elastomer as a core layer configured to be high temperature resistant and elastic; and

the high-temperature-resistant and wear-resistant layer is made of non-metallic materials, covers the outside of the high-temperature-resistant elastomer and is configured to resist high temperature and wear;

when a device to be sealed extrudes the high-temperature-resistant and wear-resistant layer, the high-temperature-resistant and wear-resistant layer and the high-temperature-resistant elastomer are sequentially deformed due to the extrusion, and the high-temperature-resistant elastomer generates resilience force due to the deformation; the non-metallic high-temperature resistant anti-wear layer is configured in such a way that when the device to be sealed is far away from the high-temperature resistant anti-wear layer, the resilience force of the high-temperature resistant elastomer is enough to drive the high-temperature resistant anti-wear layer to move towards the device to be sealed so as to keep the device to be sealed in contact with the high-temperature resistant anti-wear layer and seal the device to be sealed; when the device to be sealed rubs with the composite sealing material, the high-temperature resistant and wear-resistant layer directly contacts with the device to be sealed to generate friction, so that the friction is prevented from directly acting on the high-temperature resistant elastomer, and the friction damage of the high-temperature resistant elastomer is reduced or prevented.

Optionally, the percentage of the cross-sectional area of the high-temperature resistant elastomer to the cross-sectional area of the high-temperature resistant wear-resistant layer is more than 35% and less than 85%, so as to prolong the sealing time of the high-temperature resistant wear-resistant layer to the device to be sealed according to the roughness of the device to be sealed.

Optionally, the high-temperature resistant elastomer is made of fluororubber or TD350 sealing material.

Optionally, the high-temperature-resistant and wear-resistant layer is made of aramid fibers.

Optionally, the high temperature resistant and wear resistant layer is impregnated with a high ignition point lubricating material to provide the high temperature resistant and wear resistant layer with self-lubricity.

Optionally, the cross-sectional shape of the high-temperature resistant elastomer is circular, and the cross-sectional shape of the high-temperature resistant and wear-resistant layer is square or circular.

According to another aspect of the application, a sealing element is provided, which is made of the wear-resistant and high-temperature-resistant composite sealing material.

Optionally, the seal is helically wound from the composite sealing material.

The section of the high-temperature-resistant and wear-resistant layer is square or circular, and preferably, the sealing element is cylindrical or conical.

Optionally, the device to be sealed is a polished rod, a sealing ring is arranged at the upper end of the sealing element, the sealing ring is made of the high-temperature-resistant elastomer, the hardness of the sealing ring is greater than that of the sealing element, the sealing ring is used for preventing axial pressure from directly acting on the sealing element to cause damage to the sealing element, and when the polished rod axially jumps and is eccentric, the sealing ring has certain deviation correction compensation performance due to greater hardness.

The composite sealing material comprises a high-temperature-resistant elastomer serving as a core layer and a high-temperature-resistant wear-resistant layer coated outside the high-temperature-resistant elastomer. The high-temperature resistant elastomer has elasticity, and the high-temperature resistant and wear-resistant layer has wear resistance, so that the wear-resistant and high-temperature resistant composite sealing material achieves the effects of high temperature resistance, wear resistance and elasticity. The sealing element is made of the wear-resistant high-temperature-resistant composite sealing material. Therefore, the sealing element can also achieve the effects of high temperature resistance, wear resistance and elasticity, and the sealing duration of the sealing element is further prolonged.

The above and other objects, advantages and features of the present application will become more apparent to those skilled in the art from the following detailed description of specific embodiments thereof, taken in conjunction with the accompanying drawings.

Drawings

Some specific embodiments of the present application will be described in detail hereinafter by way of illustration and not limitation with reference to the accompanying drawings. The same reference numbers in the drawings identify the same or similar elements or components. Those skilled in the art will appreciate that the drawings are not necessarily drawn to scale. In the drawings:

FIG. 1 is a schematic cross-sectional view of a wear and high temperature resistant composite seal material according to one embodiment of the present application;

FIG. 2 is a schematic cross-sectional view of a wear and high temperature resistant composite seal material according to another embodiment of the present application;

FIG. 3a is a schematic front view of a seal according to one embodiment of the present application;

FIG. 3b is a schematic bottom view of FIG. 3 a;

FIG. 4 is a schematic block diagram of a seal according to another embodiment of the present application;

FIG. 5a is a schematic front view of a seal according to yet another embodiment of the present application;

FIG. 5b is a schematic bottom view of FIG. 5 a;

FIG. 5c is a schematic rear view of the seal ring of FIG. 5 a;

fig. 6 is a schematic structural view of a testing apparatus for testing the seal member of the present application.

The symbols in the drawings represent the following meanings:

100 of the sealing member,

10 a composite sealing material which is composed of a composite material,

1 high-temperature resistant elastomer, 2 high-temperature resistant abrasion-resistant layer,

20 a sealing ring is arranged on the inner wall of the container,

the packing box comprises a pressing sleeve, a pressing cap, a first packing, a second packing, a polish rod and a packing box 6.

Detailed Description

Example 1

FIG. 1 is a schematic cross-sectional view of a wear and high temperature resistant composite seal material according to one embodiment of the present application. FIG. 2 is a schematic cross-sectional view of a wear and high temperature resistant composite seal material according to another embodiment of the present application.

As shown in fig. 1 and also in fig. 2, the present embodiment provides a wear-resistant and high-temperature-resistant composite sealing material 10 for sealing a device to be sealed, which may generally include: a high-temperature resistant elastomer 1 and a high-temperature resistant abrasion-resistant layer 2. And a high-temperature-resistant elastic layer as a core layer, which is configured to be resistant to high temperature and have elasticity. The high-temperature resistant and wear-resistant layer 2 is made of non-metallic materials, is coated outside the high-temperature resistant elastomer 1, and is configured to be resistant to high temperature and wear. In this embodiment, the high temperature resistant and wear resistant layer is coated on the outer portion, but the elastic effect of the layer itself is not good, and the high temperature resistant elastomer 1 needs to maintain certain elasticity, and the high temperature resistant elastomer is added to the inner portion to make the layer have certain elasticity. When a device to be sealed extrudes the high-temperature-resistant and wear-resistant layer 2, the high-temperature-resistant and wear-resistant layer 2 and the high-temperature-resistant elastomer 1 sequentially deform due to the extrusion, and the high-temperature-resistant elastomer 1 generates resilience force due to the deformation; the non-metallic high-temperature resistant and wear-resistant layer 2 is configured such that when the device to be sealed is far away from the high-temperature resistant and wear-resistant layer 2, the resilience force of the high-temperature resistant elastomer is enough to drive the high-temperature resistant and wear-resistant layer 2 to move towards the device to be sealed so as to keep the device to be sealed in contact with the high-temperature resistant and wear-resistant layer 2 and seal; when the device to be sealed rubs against the composite sealing material 10, the high-temperature resistant and wear-resistant layer 2 directly contacts with the device to be sealed to generate friction, so that the friction is prevented from directly acting on the high-temperature resistant elastomer 1 which is not wear-resistant, and the friction damage of the high-temperature resistant elastomer 1 is reduced or prevented.

The high temperature resistance in the embodiment means that the composite sealing material keeps the high temperature of 120-350 ℃ which is wear-resistant according to the materials selected by the high temperature resistant elastomer and the high temperature resistant wear-resistant layer.

The wear-resistant high-temperature-resistant composite sealing material 10 comprises a high-temperature-resistant elastomer 1 serving as a core layer and a high-temperature-resistant wear-resistant layer 2 coated outside the high-temperature-resistant elastomer 1. Because the high-temperature resistant elastomer 1 has elasticity and the high-temperature resistant and wear-resistant layer 2 has wear resistance, the wear-resistant and high-temperature resistant composite sealing material 10 achieves the effects of high temperature resistance, wear resistance and elasticity.

In this embodiment, the high temperature resistant elastomer 1 is made of fluororubber or TD350 sealing material developed by tianding co-creation. Preferably, the high temperature resistant elastomer 1 is a perfluoroether rubber.

In this embodiment, the high-temperature resistant and wear-resistant layer 2 is made of aramid fiber. The aramid fiber has high wear resistance, high chemical resistance and high thermal degradation resistance. Aramid fibers are all called "aromatic polyamide fibers", and Aramid fibers are used in english. Kevlar, a trade name of DuPont, is one of the aramid fibers, namely para-aramid fiber. Para-aramid fiber is a novel high-tech synthetic fiber, has excellent performances such as superhigh strength, high modulus and high temperature resistance, acid and alkali resistance, light weight, and its intensity is 5 ~ 6 times of steel wire, and the modulus is 2 ~ 3 times of steel wire or glass fiber, and toughness is 2 times of steel wire, and weight is only about 1/5 of steel wire, under 560 degrees of temperature, does not decompose, does not melt. It has good insulating property and ageing resistance, and has long life cycle.

In this embodiment, the high temperature resistant and wear resistant layer 2 is impregnated with a high ignition point lubricating material, so that the high temperature resistant and wear resistant layer 2 has self-lubricating properties. In specific implementation, the high-temperature resistant and wear-resistant layer 2 is an aramid woven layer impregnated with a high-ignition-point lubricating material. The high-ignition-point lubricating material can adopt graphite emulsion to form a graphite layer, and the graphite has a lubricating effect and is attached to the high-temperature-resistant wear-resistant layer 2 in a high-temperature-resistant manner, so that the high-temperature-resistant wear-resistant layer 2 has self-lubricating property. When the device to be sealed of the high-temperature resistant and wear-resistant layer 2 is extruded, the graphite emulsion is extruded, and the graphite emulsion on the surface of the high-temperature resistant and wear-resistant layer 2 is increased, so that the lubricating effect is further increased.

Further, in this embodiment, the sectional area ratio of the inner high temperature resistant elastomer 1 and the outer coating high temperature resistant abrasion resistant layer 2 is the key to control the applicable conditions and the service life. The sectional area ratio of the high-temperature resistant elastomer 1 to the high-temperature resistant wear-resistant layer 2 is that when the sectional area of the high-temperature resistant elastomer 1 is large, the high-temperature resistant elastomer is suitable for a low-wear working condition, and after the high-temperature resistant wear-resistant layer 2 is consumed, the internal high-temperature resistant elastomer 1 still has a certain wear resistance; for the rough high-abrasion working condition of the device to be sealed, the sectional area of the high-temperature resistant and wear-resistant layer 2 is increased, so that the wear resistance is durable, but the sectional area of the high-temperature resistant elastomer needs to be considered, and the sectional area of the internal high-temperature resistant elastomer 1 is too small, so that the high-temperature resistant and wear-resistant layer 2 coated outside cannot provide enough resilience force to enable the high-temperature resistant and wear-resistant layer to be sealed with the device to be sealed. It is therefore necessary to improve the wear resistance while ensuring the elastomeric character of itself, depending on the actual situation. For example, the high-temperature resistant elastic material is adopted in the inner part, and the elasticity is still kept under the condition of 350 ℃. The coating is coated with a wear-resistant and temperature-resistant material which is impregnated with a lubricating material with a high burning point, and has certain self-lubricating property.

As shown in fig. 1, referring to fig. 2, the percentage of the cross-sectional area of the high temperature resistant elastomer 1 to the cross-sectional area of the high temperature resistant and wear resistant layer 2 is greater than 35% and less than 85%, so as to prolong the sealing time of the high temperature resistant and wear resistant layer to the device to be sealed according to the roughness of the device to be sealed. In specific implementation, the high-temperature resistant and wear-resistant layer 2 is an aramid woven layer impregnated with graphite emulsion, and the high-temperature resistant elastomer 1 is made of a high-temperature resistant TD350 sealing material. When the working temperature is 350 ℃, the percentage of the sectional area of the high-temperature resistant elastomer 1 to the sectional area of the high-temperature resistant abrasion-resistant layer 2 is 35%. The working temperature is 260 ℃, and the percentage of the sectional area of the high-temperature resistant elastomer 1 to the sectional area of the high-temperature resistant abrasion-resistant layer 2 is 51%. When the working temperature is 180 ℃, the percentage of the sectional area of the high-temperature resistant elastomer 1 to the sectional area of the high-temperature resistant abrasion-resistant layer 2 is 70%. When the working temperature is 120 ℃, the percentage of the sectional area of the high-temperature resistant elastomer 1 to the sectional area of the high-temperature resistant abrasion-resistant layer 2 is 85%.

As shown in fig. 1, the cross-sectional shape of the high temperature resistant elastomer 1 is circular, and the cross-sectional shape of the high temperature resistant and wear resistant layer 2 is square. As shown in fig. 2, the cross-sectional shape of the high temperature resistant elastomer 1 is circular, and the cross-sectional shape of the high temperature resistant and wear resistant layer 2 is circular. The section of the high-temperature resistant elastomer 1 is circular, and the circular shape can better prevent the self-stress damage.

Example 2

FIG. 3a is a schematic front view of a seal according to one embodiment of the present application; fig. 3b is a schematic bottom view of fig. 3 a. FIG. 4 is a schematic block diagram of a seal according to another embodiment of the present application. FIG. 5a is a schematic front view of a seal according to yet another embodiment of the present application; FIG. 5b is a schematic bottom view of FIG. 5 a; fig. 5c is a schematic rear view of the sealing ring of fig. 5 a.

Referring to fig. 3a-3b, and also to fig. 4, and also to fig. 5a, 5b, and 5c, this embodiment also provides a seal 100 made from the wear and high temperature resistant composite seal material 10 described in embodiment 1.

The sealing element 100 of the present embodiment is made of the wear-resistant and high-temperature-resistant composite sealing material 10, so that the sealing element 100 also has all the advantages of the composite sealing material 10, and thus the sealing element 100 can achieve the effects of high temperature resistance, wear resistance and elasticity, thereby improving the sealing duration of the sealing element 100.

More specifically, as shown in fig. 3a-3b, and also in fig. 4, and also in fig. 5a, 5b, and 5c, the seal 100 is formed by spirally coiling the composite sealing material 10.

Further, the section of the high temperature resistant and wear resistant layer 2 shown in fig. 1 is square, so that pressure is more uniformly applied to the high temperature resistant elastomer 1 when the high temperature resistant and wear resistant layer is extruded by the device to be sealed, and the inner surface of the high temperature resistant and wear resistant layer can completely cover the polish rod, thereby increasing the sealing property.

Referring to fig. 2, the cross section of the high temperature and wear resistant layer 2 is circular.

As shown in fig. 3a-3b, the seal 100 may be a packing, specifically a cylindrical shape that is spirally wound.

In the implementation process, the inventor finds that if the shape of the sealing element 100 is cylindrical, the upper end is too deformed and pressed by the polish rod too tightly after compression, so that friction is increased, the abrasion of the upper end is large, and the sealing is affected because the lower end is not pressed by the polish rod tightly. On the basis of this, the method is suitable for the production,

as shown in fig. 4, the seal 100 may be a packing, specifically a cone that spirals in a spiral. The seal 100 is conical in shape and undergoes axial compression and radial expansion after being compressed at the upper end, with the change in compression being most pronounced.

In this embodiment, the device to be sealed is a polish rod, as shown in fig. 5a, 5b, and 5c, a sealing ring 20 is disposed at an upper end of the sealing element 100, the sealing ring 20 is made of the high temperature resistant elastomer 1, an outer diameter of the sealing ring 20 is substantially the same as an outer diameter of the sealing element 100, and a hardness of the sealing ring 20 is greater than a hardness of the sealing element 100, so as to prevent an axial pressure from directly acting on the sealing element 100 to damage the sealing element 100, and when the polish rod has axial runout and eccentricity, the sealing ring 20 has a certain deviation correction compensation property due to the greater hardness. And because both are sealed with the polished rod, the coefficient of thermal expansion of the sealing element 100 is greater than that of the sealing ring 20, and the sealing element 100 is worn due to overlarge friction force between the sealing element and the polished rod caused by expansion at high temperature, at the moment, the sealing ring 20 can still continue to seal, and the sealing duration of the whole device is prolonged.

In the actual oil recovery process, press the cap to drive through the rotation and press the cover to remove downwards and give the packing and continue decurrent axial pressure, under the effect that receives and continuously decurrent axial pressure: 1) the axial size of the packing is reduced, so that the outer diameter of the packing is increased to closely contact with the inner wall of the oil pipe to prevent the medium from leaking outwards; 2) the size of the inner diameter of the packing is reduced, so that the inner diameter of the packing is in close contact with the outer diameter of the polish rod to realize axial dynamic sealing. The inventor finds that: because the movement track of the polished rod is not an upper straight line and a lower straight line, but is accompanied with vibration and swing all the time, namely, the movement track has a transverse movement component, if the inner diameter of the packing which plays a sealing role of the packing box and the outer diameter of the polished rod are influenced by temperature rise, the radial volume expansion of the packing is overlarge, so that the inner diameter of the packing is further reduced, the contact between the inner diameter of the packing and the outer diameter of the polished rod is too tight, the contact friction force is overlarge, under the action of the radial friction force and the transverse friction force, the inner surface of the packing is worn eccentrically too fast, crude oil is leaked from the polished rod, the sealing effect is influenced, and the environmental.

In order to solve the problem that the sealing performance is reduced after the packing is worn, the sealing material forming the packing has certain reasonable high-temperature thermal expansion property to ensure that the dynamic sealing performance is good on the premise that the friction resistance between the polish rod and the combined packing is not increased, so that different requirements are respectively required for the materials forming the packing, namely the materials forming the packing cannot be single, and the economic and reasonable sealing effect can be achieved by combining a plurality of different material groups.

The combined packing root is composed of a first packing set and a second packing set, wherein the thermal expansion coefficient of the first packing set is larger than that of the second packing set. The number of the first packing and the second packing of the combined packing can be combined according to the technical conditions of different oil fields and oil wells. The hardness of the second packing is greater than that of the first packing, the second packing is used for preventing the axial pressure from directly acting on the first packing to cause damage, and when the polished rod axially jumps and is eccentric, the second packing has certain deviation correction compensation performance due to the greater hardness. And, because both are sealed with the polished rod, two kinds of materials expend with heat and contract with cold differently, even if one is sealed the inefficacy by high temperature wear, another can also continue to seal, has increased the sealed time of whole equipment.

More specifically, referring to fig. 5a, 5b and 5c, the sealing element 100 is a combined packing, and in this embodiment, the upper portion is a sealing ring 20, i.e., a second packing, and the lower portion is a cylindrical packing or a conical packing, i.e., a first packing.

In the specific implementation:

a first disc root: is formed by winding a rectangular strip with certain length and appearance. The first disc root is made of a wear-resistant and high-temperature-resistant composite sealing material 10, referring to fig. 1, the wear-resistant and high-temperature-resistant composite sealing material 10 is formed by filling a round TD350 or perfluoro ether rubber, namely a high-temperature-resistant rubber body, in a wrapping layer, namely a high-temperature-resistant and wear-resistant layer 1, wherein the wrapping layer is formed by weaving a lubricating material with a rectangular 15 x 15mm outer cross section and is made of aramid fiber impregnated with a high-ignition point. The lubricating material can be high-temperature-resistant graphite emulsion, so that the frictional resistance between the outer diameter of the polish rod and the inner diameter of the first packing in the up-and-down moving process is reduced, the loss of idle work is reduced, the oil extraction efficiency is improved, and the service life of the combined packing is prolonged.

A second packing: referring to fig. 5c, the sealing ring 20 made of TD350 or perfluoro-ether rubber and having 45 ° through chamfer cut of about 45 ° is provided for easy mounting on or dismounting from the polish rod.

Fig. 6 is a schematic structural view of a testing apparatus for testing the seal member of the present application. The test device is composed of a pressing sleeve a, a pressing cap b, a first packing c, a second packing d and a packing box 6. When the first packing c and the second packing d are replaced in the oil field, the polished rod 4 does not depart from the packing box 6, and in order to realize the installation and the disassembly of the first packing c and the second packing d on the polished rod 4, a bevel cut penetrating about 45 degrees is obliquely cut on the first packing c. Because the packing is elastic, when the packing is installed, the bottom end or the top end of the packing is sleeved on the polish rod 4, the packing is rotated, and the rest part is screwed in and sleeved on the polish rod 4. After the packing is damaged, the bottom end or the top end of the packing is pulled towards the direction far away from the polish rod 4, the packing is rotated, and the rest part is screwed out of the polish rod 4.

After the combined packing is installed in the packing box, the internal thread of the pressing cap b and the external thread on the upper part of the packing box d are screwed together through the threads. When the pressing cap b is rotated clockwise, the pressing cap b drives the pressing sleeve a to move axially downwards, and meanwhile, a downward pressing axial force is generated on a combined packing formed by the first packing c and the second packing d. Under the action of the downward axial force, the combined packing generates radial force due to the plasticity of the combined packing and is respectively in close contact with the inner diameter of the oil pipe and the outer diameter of the polish rod. Meanwhile, under the action and extrusion of a high-temperature and high-pressure oil-gas mixed medium, a high-ignition-point lubricating material impregnated by the outer wear-resistant and high-temperature-resistant aramid braid layer of the second packing d, a core part TD260 material (TD 260 of Tianding Co-creation company) and a lubricating agent core-based graphite blended in the TD260 material of the second packing are extruded, so that the combined packing has the self-lubricating characteristic, and lubricating surface contact is formed between contact surfaces respectively.

Firstly, the pumping unit is stopped at a position close to a bottom dead center, braking is carried out, power is cut off, and then the blowout preventer on the lower portion of the pumping unit is closed. Because the external screw thread on the upper portion of the packing box 6 is the dextrorotation and the second packing d is a strip-shaped belt with a square section, see fig. 6 in detail, the second packing d needs to be screwed into the packing box 6 from the upper end of the packing box 6 downwards around the polish rod 4 in a clockwise direction. Then, the first packing c is loaded from the upper end of the packing box 6. The pressing sleeve a is arranged on the upper part of the packing box 6. The pressing cap b is screwed downwards clockwise through the thread fit on the upper part of the packing box 6, so that the pressing sleeve a moves downwards under the action of downward axial force generated by clockwise screwing the thread of the pressing cap b, the axial height of the first packing c and the second packing d is compressed, the outer diameter size is increased, the inner diameter size is reduced, and the sealing of an annular space between the packing box 6 and the polish rod 4 is realized. And then, a lower oil inlet and an upper oil return port of the packing box 6 are respectively connected with a hydraulic oil pump and a connecting pipeline (not shown in the figure) of the hydraulic oil pump. After the connection, the sealing test can be carried out. The working conditions of high temperature and high pressure oil gas can be realized by a temperature control box and a hydraulic pump. The order when the combination packing is disassembled and assembled is opposite to the order when the combination packing is assembled.

The effective sealing time is more than or equal to 240h under the working condition of 260 ℃.

It is to be noted that, unless otherwise specified, technical or scientific terms used herein shall have the ordinary meaning as understood by those skilled in the art to which this application belongs.

In the description of the present application, it is to be understood that the terms "central," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," "circumferential," and the like are used in the orientations and positional relationships indicated in the drawings for convenience in describing the present application and to simplify the description, and are not intended to indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and are therefore not to be considered limiting of the present application.

Furthermore, the terms "first", "second", etc. are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. In the description of the present application, "a plurality" means two or more unless specifically defined otherwise.

In this application, unless expressly stated or limited otherwise, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can include, for example, fixed connections, removable connections, or integral parts; can be mechanically or electrically connected; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meaning of the above terms in the present application can be understood by those of ordinary skill in the art as appropriate.

In this application, unless expressly stated or limited otherwise, the first feature "on" or "under" the second feature may be directly contacting the first and second features or indirectly contacting the first and second features through intervening media. Also, a first feature "on," "over," and "above" a second feature may be directly or diagonally above the second feature, or may simply indicate that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature may be directly under or obliquely under the first feature, or may simply mean that the first feature is at a lesser elevation than the second feature.

The above description is only for the preferred embodiment of the present application, but the scope of the present application is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present application should be covered within the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.